1. Field of the Invention
The present invention relates to heat transfer insulated parts which can be used as heat transfer parts, high heat transfer substrates and..so forth to be provided in Multi Layer Ceramic Packages (FLLCP), etc. and a manufacturing method thereof.
2. Description of the Background Art
Multilayer ceramic packages have a structure in which sintered alumina are stacked. The multilayer cemraic packages are provided with heat transfer substrates on which LSI chips or the like are mounted and heat transfer caps. As conventional heat transfer substrate portions and heat transfer cap portions, Cu-W sintered body, BeO sintered body, SiC sintered body, and AlN sintered body etc. are employed.
The Cu-W sintered body, as it is not an electric insulator, could not be used for package parts having a structure in which electric short of the parts is a problem. Accordingly, a package in which alumina multilayers and the Cu-W sintered body are integrally encapsulated has been mainly used in a product having no problem of electric short through the Cu-W.
However, for some applications, it was desirabale that the excellent heat dissipation capacity of the Cu-W sintered body was utilized. In such a case, an alumina sheet is stacked on a Cu-W sintered body, or an insulating film such as an Al.sub.2 O.sub.3 film is deposited on the surface of the Cu-W sintered body. However, in the case where an alumina sheet is stacked, problems occur such as that the dimension of the entire package is large, the heat dissipation capacity decreases, or a complicated package structure costs much. In the case where an insulating film such as an Al.sub.2 O.sub.3 film is deposited, Cu diffuses from a heat transfer substrate into the insulating film to reach the surface of the insulating film due to heating at 900.degree. C., for example, in the package assembling process, so that they have caused problems such as inferior insulating.
When SiC or AlN sintered body is employed, because of the large difference of thermal expansion coefficient between the heat transfer substrate and multilayered alumina, they had a problem that cracks occur at the junction in the glass encapsulation process.
In case of the BeO sintered body, since it includes harmful beryllium, it is facing a difficult situation which might lead to stop of manufacturing in view of a problem of environmental pollution.